1. Field of the Invention
The present invention relates to a composite electrode which is used for welding, generally of the resistance welding type, in which a workpiece made of copper or the like is welded by applying high current to a high-melting point metal or alloy so as to generate high temperature heat at the same time as high pressure is applied to the electrode (in some cases called pressure welding, fusing or diffusion welding because no molten metal portion is produced during the welding process), and also for heat caulking in which a stainless steel material is thermally deformed and fixed and the like.
2. Description of the Prior Art
As shown in FIG. 1, a conventional electrode body for resistance welding comprises an electrode 1 made of a high-melting point metal or alloy which is inserted into a hole formed in an electrode holder 3 made of a copper alloy and fixed to the holder 3 by utilizing a brazing portion 7 provided therebetween.
When the electrode 1 made of a high-melting point metal or alloy in the conventional electrode body is deformed due to use or becomes worn due to oxidation, the electrode 1 becomes separated from the electrode holder 3 and a new electrode 1 is mounted therein.
The above-described conventional electrode body involves the following problems, however. Firstly, it takes time to do the brazing work when a new electrode is provided. Moreover, the hole formed in the electrode holder 3 becomes enlarged after the electrode 1 has been replaced many times and filler metal removed. This leads to difficulty being encountered in properly centering the electrode.